Long Term Evolution (LTE) is wireless network technology based on orthogonal frequency-division multiplexing (OFDM). OFDM is a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio broadcasting, DSL Internet access, wireless networks, powerline networks, and 4G mobile communications.
Multiple-Input Multiple-Output (MIMO) is a multi-antenna technique implemented in LTE. In addition to MIMO, LTE networks also use beamforming techniques. Transmit beamforming works by exploiting the interference patterns observed whenever the same signal is transmitted from two or more spatially separated transmission points.
Sounding reference signals (SRS) are transmitted on the LTE uplink and allow the network to estimate the quality of the uplink channel for a specific User Equipment (UE) at different frequencies. Estimating uplink channel quality allows evolved Node B (eNodeB) network elements to make smart decisions for resource allocation for uplink transmission, link adaptation and to decode transmitted data from UE.
Currently, the network node (eNodeB) must select an explicit SRS pattern and schedule resource blocks and transmit this information to UE. UE responds to the instructions provided by the network node with the selected SRS pattern at the scheduled time. Requiring the network node to select SRS patterns and schedule resource blocks consumes valuable network node resources.